This uses the dorny/paths-filter action to determine which services in a monorepo have changed and then splits the output by language based on the directory structure

paths-filter-by-language.yaml

name: "Determine Services Changed"
description: "determine which services changed"
inputs:
  github-token:
    description: github token (passed to paths-filter action)
    required: false
    default: ""
outputs:
  go_services:
    description: "JSON array of changed Go services"
    value: ${{ steps.matrices.outputs.go_services }}
  node_services:
    description: "JSON array of changed Node/React services"
    value: ${{ steps.matrices.outputs.node_services }}
  python_services:
    description: "JSON array of changed Python services"
    value: ${{ steps.matrices.outputs.python_services }}

runs:
  using: "composite"
  steps:
    # Because this is a mono-repo, we must determine which applications have changed
    - name: Paths Changes Filter
      id: filter
      uses: dorny/paths-filter@de90cc6fb38fc0963ad72b210f1f284cd68cea36 # v3.0.2
      with:
        token: ${{ inputs.github-token }}
        filters: .github/utils/file-filters.yaml
    - name: Generate matrices
      id: matrices
      shell: bash
      run: |
        # TODO: move this logic out of inline script
        set -euo pipefail

        # `changes` is a JSON array of filter names that matched any file
        filters='${{ steps.filter.outputs.changes }}'

        # for testing
        go_json=$(jq -c '[ .[] | select(startswith("go/")) ]'   <<<"$filters")
        node_json=$(jq -c '[ .[] | select(startswith("node/") or startswith("react/")) ]'<<<"$filters")
        python_json=$(jq -c '[ .[] | select(startswith("python/")) ]'<<<"$filters")

        echo "go_services=$go_json"   >>"$GITHUB_OUTPUT"
        echo "node_services=$node_json" >>"$GITHUB_OUTPUT"
        echo "python_services=$python_json" >>"$GITHUB_OUTPUT"